A. Hard water may have gotten a bad rap because it can suppress the lather of the soaps used in cleansers and shampoos. But the addition of synthetic detergents to these products has obviated that problem, says Mort Westman, president of Westman Associates, a research and development consultancy in Oak Brook, Illinois. Mort, the cosmetic chemist to whom we most often turn when we're trying to untangle a particularly knotty beauty dilemma, always offers an unexpected piece of interesting information. This time, he suggested that the only drawback of very soft water is that it could encourage over-rinsing of rinse-out products (which could lead to dry skin or hair) in an effort to eliminate the slimy feel it sometimes leaves.